In U.S. Pat. No. 5,958,275, a planar material is passed through a serpentine wave guide that has more than one straight segment The planar material is passed in a direction that is perpendicular to the propagation of an electromagnetic wave in each straight segment. The planar material is passed through a series of diagonal openings to account for attenuation of the electromagnetic wave.
In Metaxas et al, “Industrial Microwave Heating,” Peregrinus on behalf of the Institution of Electrical Engineers, London, United Kingdom and co-pending and co-assigned application# 09/372,749, a planar material is passed in a direction parallel to the propagation of the electromagnetic wave. In Metaxas and the '749 application, it is preferable to keep the electromagnetic wave in TE10 mode so that there is a peak half way between the top conducting surface and the bottom conducting surface. In Metaxas and the '749 application, the width of the exposure region is limited by the size of the waveguide. In order to dry carpets, rugs, or other relatively wide materials, the waveguide would have to be prohibitively tall. There is a need for an exposure chamber that can be used to rapidly and continuously heat relatively wide materials.